Furnace-bottom and process of making and repairing same.



m. 7| 4,5e5. N Patented Nov. 25-, I902.

num onu. FURNACE'BOTTOM AND PROEESS OF MAKING AND REPAIRING SAME.

(Application filed Aug. 16, 1902.) 0 Model.)

WITNESSES, [NVZSNTOR J r? g/bA n D uni 2rd I (5 way AT NEY.

m: mums wire: co, FHOTO-LlTHO-, wAsumG'roN. n. n.

NIT ED STATES JOHN DUNFORD, OF JOIINSTOWN, PENNSYLVANIA.

FURNACE-BOTTOM AND PROCESS OF MAKING AND REPAIRING SAME.

SPECIFICATION forming part of Letters Patent No. 714,565, dated November25, 1902.

Application filed August 16,1902. Serial No. 119,877. (No model.)

To all whom it may concern.-

Be it known that I, JOHN DUNFORD, a citizen of the United States,residing at J ohnstown, in the county of Cambria and State ofPennsylvania, have invented certain new and usefulImprovementsinFurnace-Bottoms and Processes of Making and RepairingSame; and I do hereby declare thefollowing to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

Although my process may be applied to reverberatory heatingfurna'ces,pit-furnaces,

' open-hearth steelmelting furnaces,.&c., I

will for the sake of simplicity confine my description and illustrationto open-hearth steel melting furnaces, as the other applications will beobvious to those familiar with the art, and while steam or various gasesunder pressure may be used in conducting that part of my processrelating to cleaning out cavities in the furnace-bottom I will confinemy description to the use of compressed air for this purpose.

Incidental to the process of manufacturing steel in an open-hearthfurnace it frequently happens that the bottom of the furnace I isscorified or cut locally, with the result that after tapping the melttherefrom one or more cavities or depressions may be found in the hearthof the furnace. Such cavities or depressions are sometimes ofconsiderable size, and the molten metal orslag held therein should becleanedout before the necessary repairs previous to the next heat can bemade. If the slag or metal is not all removed or drained from suchcavities, it is difficult or impossible to secure proper or sufficientcohesion between the refractory material used to repair and fill saidcavities and the adjacent portions of the bottom. As a consequence suchpatches or repairs are raised up or eroded during the following heat,with resulting additional injury to the hearth or fur nace-bottom. Theprocess of making the furnace-bottom in the first instance and ofcleaning and repairing same afterward is ordinarily known in the art asmaking bottom.

Heretofore it has been customary to use rabbles for dashing or cleaningthe hot metal and slag out of the depression, and the labor incidentalto this procedure is very arduous and expensive. The rabbles are veryheavy and cumbersome appliances. A large number of them is required foreach operation, and after having been used once each rabble must bedressed by a blacksmith, thus increasing the cost of this operation verylargely. The worst defect connected with the use of rabbles is theimpossibility of effectively and completely drying and draining thecavities referred to,

with the result, as hereinbefore stated, that it may be necessary torepair the bottom very frequently. I

My invention remedies all the above-mentioned disadvantages, and abetter furnace bottom or hearth results from my improved process ofmaking and repairing same.

In practicing my invention I employ a pressure-pipe carrying compressedair, provided With the necessary valves and connections attachedthereto. If after tapping a furnace it is found that there is one ormore pools of molten slag or metal in the bottom of said furnace, Iintroduce the air-pipe into the furnace through the charging-door andplace the end of said pipe within or near the hot metal or slag. The airis then turned on, and said slag or metal is ejected much morethoroughly and in a very small fraction of the time required by theordinary method, outlined hereinbefore.

As can be readily understood, my process is extremely simple and verycheap. Moreover, it is highly eflicient, because I can completely drainevery cavity or depression of the hot metal or slag contained therein,with the result that the new refractory material placed in said cavitiesor depressions will adhere to the adjoining portions of the bottom orhearth, which are composed of similar material. Hence the repairs thusmade are more permanent and the bottom more homogeneous.

With imperfect cleaning or drainage of the cavities resultant from theold method the refractory repairs are not in direct contact with andsintered to the old bottom, but are separated therefrom by portion ofthe metal or slag, with the result that said patches or repairs risewith succeeding heats and are destroyed, thus forming the cavity anew,all of which is prevented by myimproved process,

which thoroughly cleans the cavities.

Another advantage resulting from my improved process is that littlecooling of the,

. takes a longtime the furnace is in consequence greatly cooled, thuscausing additional delay the workin g temperature.

As my process is conducted very quickly and completely, it constitutes avaluable improvement in repairing and making furnacebottoms. Afurtherandveryimportantadvantage' of my process is that one man alone can veryeasily perform the operation of cleaning the furnace-bottom, while ifrabbles are used a number of men are required to handle each rabble,thus incurring aconsiderable expense in labor, which is entirelyeliminated by my process.

Having thus given a general description of my invention and itsadvantages, I will now, in order to make the matter more clear, refer tothe annexed drawing, showing a vertical cross sectional elevation of anopen hearth furnace which forms part of this specification.

1 represents the furnace walls and roof, generally built of refractorybricks.

2 is the bottom or hearth, made of loose refractory material, set orsintered by raising the temperature until the material hardens into asolid mass.

3 is the air-port; 4E,'the gas-ports.

5 is the charging-opening. 6 is a door for closing said opening, and 7is the chargingfioor or standing,

8 is the tapping-hole, which is placed at the lowest point of the bottomand is closed by refractory material during the melt.

9 is intended to showacavity or depression such as is sometimes cut inthe bottom or due to the time required for heating again to hearth offurnaces by the action of the slag for the molten metal and which, forconvenience of illustration, is shown situated opposite thetapping-hole, but may be above or on either side thereof. No matter inwhich portion of the hearth these cavities occur, they can be reached bymerely introducing a sufficient length of pipe or by bending the same.

10 represents the pool of molten slag or metal that collects in suchcavities and which should be completelyremoved or drained out before agood repair can be made. In the illustration a man is indicated asholding a high-pressure pipe 11, which is connected at one end to aflexible connection or hose 12, which latter is attached to acompressed-air main. (Not shown.)

13 is a piece of ordinary gas-pipe secured to the pressure-pipe 11 bymeans of the intermediate valve 14,which regulates the amount of airadmitted. The destruction of the pipe 13 may be prevented in part byusing athick wash of lime, in which it is dipped from time to time.

An additional advantage of my process when the gas is left on thefurnace is that in the act of blowing the slag or molten metal outof acavity heat is generated by the action of the compressed air on the hotgas present in the furnace-chamber after the manner of a blowpipe, andthe metal or slag is rendered fiuid thereby.

In addition to using my process for cleaning out and repairing thelarger cavities in the hearth of a furnace, Ialso use the same duringthe making of the original bottom, the refractory material for which, inordinary practice, is deposited in comparatively thin layers, each ofwhich is baked or sintered to the preceding one, this being continueduntil the bottom is of the required thickness and form. During theprocess of making the original bottom in this manner soot, ashes,brick-spalls, and other foreign matter may accumulate on the surface ofa layer, which will prevent to a certain extent the proper cohesionthereto of the succeeding layer, and to obviate this difficulty I cleanthe surface by use of my air-jet preparatory to the deposition ofanother layer, thus permitting the succeeding deposits to come intodirect contact with the similar material of prior layers,- and therebybecome sintered to them, thus forming a solid and practicallyhomogeneous mass without the intervention of foreign matter. Thisprocess, therefore, makes a more solid bottom and one which will wearand last much longer than one containing admixtures of foreign material,as can be readily understood.

Having thus given a general description of my invention, what I claim,and desire to secure by Letters Patent, is

1. The process of cleaning and repairing furnace-bottoms, which consistsin the ejection of slag or metal from cavities therein, by

the action of fluid under pressure, then depositing refractory materialin said cavities and baking or sintering the same.

2. A step in the process of repairing furnace-bottoms, which consists inthe ejection of slag or metal from-cavities therein by the action of airunder pressure issuing from a pipe, the open end of which is insertedin, or directed to said cavities.

3. Theprocessofcleaningfurnace-bottoms, which consists in maintaining aflow of gas in the furnace; heating the slag or metal concontact withand baked or sintered t0 the surfaces of the previous layers, after saidprevious layers have been cleaned and freed from foreign material by theaction of an air-blast. In testimony whereof I hereto affix my signaturein the presence of two Witnesses.

JOHN DUNFORD.

Witnesses:

J. R. WEMLINGER, STONE EDELEN.

